Dynamometer systems of various types are used to determine statically the performance characteristics of motors and engines of various types and of vehicles powered by such motors and engines. In general, dynamometer systems for vehicles include some form of test stand structure, such as an inertial roller, that rotatingly supports the vehicle's drive wheel(s). During operation, the dynamometer system allows the vehicle to remain in a stationary fixed position while engine or motor drives the vehicle's wheel(s) which, in turn, drives the inertial roller.
A dynamometer system typically includes various devices for physically imposing loads on the vehicle wheel or wheels as it or they rotate, and devices for measuring, for example, the torque imposed on the wheel(s) or the simulated speed or acceleration of the vehicle by measuring revolutions per minute (rpm) of the wheel(s) versus time and for calculating other performance factors of interest such as, for example, horsepower, engine torque, velocity, distance traveled, etc.
It is apparent that the inertial roller is a critical element of the dynamometer system as the inertial roller(s) supports the weight of the vehicle and absorbs the driving forces imposed by the vehicle on the wheel(s), couples the driving forces imposed on the vehicle wheels to the measurement devices and couples loads imposed by the system to the driving wheels. The inertial roller assembly must, therefore, allow the roller to rotate freely and precisely while supporting very large static and dynamic loads.
There are commonly three basic configurations of test stands and inertial rollers, namely, in-ground configuration, a below ground configuration and a mobile configuration. In-ground configurations comprise an installation where the test stand is generally at ground level and the roller assembly is located below ground level in, for example, a pit. Above ground configurations comprise an installation where the test stand and roller assembly are raised above ground level. Mobile configurations, in turn, are similar to above-ground installations, but the test stand and roller assembly are mounted on or in to some form of trailer or some other mobile vehicle. The roller assemblies, however, customarily follow a common design regardless of whether the installation is in-ground, above-ground or mobile.
As illustrated in FIGS. 1A-1H, a typical inertial roller assembly is a stand-alone structure which comprises load bearing and support/reinforcement beams that, at a minimum, enclose the roller and the support bearings which facilitate rotation of the roller axle. In most instances, the roller assembly further supports and includes, for example, the inertial roller, a torque transducer, such as a strain gauge device for measuring a driving torque imposed on the roller by the driven wheels of the vehicle, a speed sensor for measuring a rotational speed of the roller and a torque load device such as an eddy current brake or a water brake for imposing a torque load on the roller.
As is apparent from FIGS. 1A-1H, the typical inertial roller assembly structure is completely self-contained and is essentially independent of the nature of the installation in which it is used. That is, the same inertial roller assembly structure can be used in an above-ground installation, where the assembly will merely stand upon the floor and will be surrounded by a platform upon which the vehicle will be supported or in an in-ground installation where the assembly will be mounted within a pit and the vehicle will be supported by the surrounding ground or floor. A mobile installation will be similar to an above-ground installation except that the inertial roller assembly structure will either be mounted into an opening or space formed in the trailer structure or will be incorporate into the trailer structure.
It is apparent that the methods of the prior art are advantageous in that the same roller assembly structure can be used for either an in-ground, an above-ground or a mobile installation thus and requires only a suitable space to receive the roller assembly structure, such as a pit for an in-ground installation, a “pit” or an “opening” in a trailer structure or merely a suitable floor space in an above-ground installation. However, due to the numerous components forming the framework for the roller assembly structure, conventional roller assembly structures, according to the prior art, are generally relatively complex and consequently expensive to manufacture and/or construct. That is, the prior art roller assembly structures require many components or elements, many structural stock cuts and many welds in order to produce a structure capable of meeting all possible requirements for the roller assembly structure.
Three of the primary structural requirements of a roller assembly structure are to securely support the roller and thus the driven wheel or wheels of the vehicle at a fixed height against the weight of the vehicle, to securely support the roller against horizontal motion along the axis of thrust of the driven wheel or wheels, that is, along the fore/aft axis relative to the nominal direction of motion of the vehicle, and to support the roller against torsional forces imposed by the driven wheel or wheels. At least the second and the third of these structural requirements, that is, that the roller assembly structure support the roller against horizontal and torsional forces, typically require not only that the roller assembly structure itself be constructed to resist these forces, but also that the roller assembly structure be connected to or braced by the installation site, such as by being bolted to the floor.
As shown in FIGS. 1A and 1B, the roller assembly framework for a prior manufactured by Land & Sea, Inc. of North Salem, N.H. generally comprises a box like structure 100 having four corner vertical supports 102 and upper and lower horizontal longitudinal supports 104, 106 which interconnect each pair of the corner vertical supports 102 with one another. A plurality of spaced apart diagonal and vertical supports 108 and 110 interconnect and reinforce the upper and the lower horizontal longitudinal supports 104, 106 with one another. In addition, this prior art roller assembly framework includes two lower horizontal transverse supports 112 which interconnect two adjacent corner vertical supports with one another and also provide support of a bearing. A couple of horizontal and vertical supports 114, 116 are connected to the lower horizontal transverse support 112 and reinforce the same. A floor mounting pad 118 is located at the bottom of each one of the four corner vertical supports 102 for securing the roller assembly structure to the floor. As shown in FIG. 1A, a bearing 120 supports each opposed end of an axle to facilitate rotation of the roller 114.
FIGS. 1C-1H show a variety of other known roller assembly structures which, as can be seen in the drawings, are all quite complex to manufacture and assemble.
Wherefore, it is an object of the present invention to overcome the above mentioned shortcomings and drawbacks associated with the prior art roller assembly structures.